Use of boranocarbonates in a photographic reversal process

ABSTRACT

A REVERSAL PROCESS IN THE PRODUCTION OF POSITIVE PHOTOGRAPHIC IMAGES, WHEREIN A BOROANOCARBONATE IS USED AS A FOGGING AGENT IN THE SECOND DEVELOPMENT STEP.

United States Patent O 3,563,746 USE OF BORANOCARBONATES IN A PHOTO- GRAPHIC REVERSAL PROCESS Otto Ernst and Eberhard Gunther, Leverkusen, Heinz Meckl, Cologne-Flittard, Herbert Odenbach, Bergedorf, Neukirchen, and Willibald Pelz, Opladen, Germany, assignors to Agfa-Gevaert Aktiengesellschaft, Leverkusen, Germany, a corporation of Germany No Drawing. Filed Jan. 27, 1969, Ser. No. 794,397 Claims priority, application Germany, Feb. 14, 1968, P 16 22 258.5 Int. Cl. G03c 5/50 [1.8. Cl. 96-59 6 Claims ABSTRACT OF THE DISCLOSURE A reversal process in the production of positive photographic images, wherein a boroanocarbonate is used as a fogging agent in the second development step.

This invention relates to an improved reversal process for use in the production of positive photographic images.

In the known photographic reversal processes for use in the production of positive black-and-white or coloured photographic images the photographic material is exposed to produce an image and is then developed in a first developer which is a conventional black-and-white developer. It is then exposed uniformly and this exposed material is subjected to a second development with a blackand-white developer or colour developer. The processing is completed by fixing or bleach fixing the photographic material.

This reversal process would be considered simplified if the uniform reversal re-exposure could be avoided. In particular, for example, the usual measures for preventing exposure of the photographic material to light during the first development, i.e. the incorporation of light valves or similar devices would be obviated.

It is known that the uniform exposure can be completely or partly avoided by using chemical fogging agents which are added to the second developer or to a preliminary bath. Sulphur-containing compounds, alkylated diamines, borazanes and other reducing agents such as alkali metal boranates, have been described for this purpose.

None of these agents, however, satisfy the requirements in practice because they do not reduce suificiently, they have insufficient stability in alkaline developer compositions or because they have other adverse effects on the photographic properties of the material. The photographic treatment baths may also be physiologically harmful.

It is an object of the invention to modify photographic reversal processes in such a way that the uniform reexposure step is no longer necessary. Another object of the invention is to provide new chemical fogging agents which have sufficient stability in alkaline photographic treatment baths and which enable complete development of the silver halide emulsion layers.

It has now been found that the uniform re-exposure can be avoided in photographic reversal processes if, instead of carrying out this exposure, water-soluble boranocarbonates are used as chemical fogging agents.

Suitable compounds include those of the following formula:

in which X represents two monovalent cations or one divalent cation.

Suitable compounds are, for example, alkali metal or alkaline-earth metal boranocarbonates, especially sodium or potassium boranocarbonate.

The compounds to be used according to the invention can be prepared by the process described in the Journal Inorganic Chemistry, vol. 6 (1967), pp. 817-822.

The process according to the invention may be used in the production both of photographic black-and-white reversal images and photographic colour reversal images. Owing to the great practical importance of the last mentioned reversal process, the process according to the invention is preferably used in the production of colour reversal images.

The photographic materials to be worked up may have the usual compositions.

The materials used in the production of colour reversal images are multi-layer films on transparent support layers made, for example, of cellulose esters, polyesters or polycarbonates or multi-layer materials on paper supports. The usual colour reversal materials contain a blue sensitive silver halide emulsion layer with a colour coupler for the production of the yellow partial image, a green sensitive silver halide emulsion layer with a coupler for the production of the magenta partial image and a red sensitive silver halide emulsion layer with a colour coupler for the production of the cyan partial image.

The process according to the invention is, of course, independent of the format of the colour photographic emulsion which is to be worked up. It can be used equally successfully for miniature films, narrow gauge colour photographic films or colour photographic paper.

The process according to the invention can be used successfully in the production of coloured photographic images by the so-called silver dye bleaching process in r which layers which already contain the dye for the particular partial image are used in known manner. The dyes, generally azo dyes, are then bleached in the dye bleaching bath in the areas corresponding to the silver image produced during development.

The boranocarbonates to be used according to the invention can be introduced into the process in a bath containing an aqueous solution thereof preceding the second development; they may also be added to the second developer. In view of the excellent stability of the boranocarbonates in alkaline aqueous solutions, these compounds can be used especially advantageously in the second developer without any harmful effects.

The concentration of the boranocarbonates in the treatment baths may vary within wide limits. The optimum concentration can easily be found by a few simple tests and can be adapted according to the special requirements of the photographic material or of the reversal process. Quantities of between 0.05 and 5 g./l. of treatment bath have generally proved to be suiiicient. Concentrations of between 0.1 and 3 g. especially between 0.8 and 2.5 g. are preferred.

The advantages of the process according to the invention lie in the excellent stability of the treatment baths which contain the chemical fogging agents. The intensity of the boranocarbonates as fogging agents is also of special importance since it lies in a particularly advantageous region so that complete development of the reverse materials obtained in accordance with the invention is possible without the photographic properties of the colour reversal materials being impaired in any way by excessive activity. Any dyes present, for example, are not attacked by the boranocarbonates. One special advantage which has hitherto not been observed with the use of chemical fogging agents is the improvement of the graininess which can in many cases be observed to be produced when employing the method according to the invention.

EXAMPLE 1 A colour photographic multi-layered material having a red sensitive, a green sensitive and a blue sensitive silver halide emulsion layer containing colour couplers for the particular patrial images in the light sensitive layers is exposed in a sensitometer behind a grey step wedge in the usual manner.

The exposed colour film is then developed in a blackand-white first developer solution of the following composition for 18 minutes at a temperature of 20 C.

Sodium hexametapbosphate g 2.0 p-Methylaminophenol g 3.0 Sodium sulphite g 50.0 Hydroquinone g 6.0 Sodium carbonate g 40.0 Potassium thiocynate g 2.5 Potassium bromide g 2.0

Potassium iodide (0.1% aqueous solution) ml 6 Water up to 1 litre.

The film is then imersed for 4 minutes at a temperature of 19 C. in a stop bath consisting of a 3 sodium acetate solution which has been adjusted to pH 5.2 by the addition of acetic acid.

It is now washed for 10 minutes, and the second development is then carried out for 14 minutes at 20 C., using a colour forming developer of the following composition:

Potassium boranocarbonate g 1.0 Sodium hexametaphosphate g 2.0 Sodium sulphite g 5.0 N,N-diethylparaphenylenediamine sulphate g 5.0 Hydroxylamine sulphate g 1.2 Potassium carbonate g 75.0 50% ethylene diamine ml 16 Water up to 1 litre.

The colour developer is produced by first dissolving all the ingredients other than the potassium boranocarbonate, in 800 ml. of water. An aqueous solution of the fogging agent is then added and the solution is made up to 1000 ml. with water.

After the second development, the film is again washed for about 20 minutes and is then treated with the following bleaching bath.

Potassium ferricyanide 100 Potassium bromide 20.0 Disodium phosphate 1.20

Water up to 1 litre.

The pH of the bleaching bath is adjusted to 5.2 with acetic acid.

The film is then again washed for about minutes and fixed for the same length of time in the following fixing bath.

G. Sodium hexametaphosphate 1.0 Borax 15.0 Sodium sulphite 10.0 Crystallised sodium thiosulphate 200.0

Water up to 1 litre (pH 8.8).

After a further washing, the processed material is immersed in a 0.2% aqueous solution of 2 ml. of tetrapropylene benzene sulphonate (pH not below 6.5) and then dried.

Another strip of the material described above is worked up in a similar manner to that described above. Before carrying out the colour development, however, uniform exposure is accomplished in the usual manner and colour development is carried out with the same bath but without potassium boranocarbonate.

The sensitometric comparison of the resulting positive step wedges shows that the procedure according to the invention is completely equivalent as regard gradation and sensitivity to the convensional method which includes a reversal re-exposure. The step wedge obtained by the procedure according to the invention, however, has a considerably finer colour grain.

EXAMPLE 2 A colour photographic reversal material on a layer support of paper is exposed in a sensitometer behind a step wedge.

It is then developed in the black-and-white developer solution of the following composition for 5 minutes at 20 C.

G. Sodium hexametaphosphate 2.0 Anhydrous sodium sulphite 20.0 p-Methylaminophenol 1.5 Hydroquinone 4.0 Potassium bromide 0.5 Borax 20.0 Sodium hydroxide 3.0 Benzotriazole 0.1

Water up to 1 litre.

After immersion in a stop bath followed by washing, the material is treated with the following colour developer solution for 8 minutes at 20 C. without exposure.

Sodium hexametaphosphate 2.0 Hydroxylamine sulphate 4.0 Anhydrous sodium sulphite 4.0 Potassium bromide 1.0

Anhydrous potassium carbonate 100.0 N-butyl-N-w-sulphobutyl-p-phenylenediamine 5.0 Potassium boranocarbonate 0.1 Water up to 1 litre.

After the second development the material is further processed as described in Example 1.

Comparison with the conventional method of procedure gives the same result. Well covered shades and light areas are obtained in pure colours with fully developed gradation.

EXAMPLE 3 A light sensitive photographic multi-layer material which is suitable for use in the negative-positive process in the silver dye bleaching process, which contains diffusion-resistant azo dyes in the individual layers and which consists of a red sensitive silver bromide emulsion layer which is situated on the support layer and contains a cyan azo dye, a green sensitive silver bromide layer which contains a magenta dye, a yellow filter layer and an uppermost, blue sensitive silver bromide layer which contains a yellow dye, is exposed under an original to be copied and is then processed at 20 C. as follows:

Mins. (1) First developer 10 (2) Washing 5 (3) Hardening bath 5 (4) Washing S (5) Silver bleaching bath 5 (6) Washing 5 (7) Second developer 1O (8) Washing 5 (9) Dye bleaching bath 15 (10) Washing 5 (11) Bleach fixing bath 10 (12) Washing 10 (13) Drying 10 The baths used have the following compositions.

uarmcroaocmuque Potassium thiocyanate 2.4 Water up to 1000 ml.

Hardening bath:

Sodium bicarbonate g 40.0 30% Formalin ml 25 Water up to 1000 ml. (pH 10.8).

Silver bleaching bath:

Potassium bichromate g 10.0 Sulphuric acid conc. ml 25 Water up to 1000 ml. (pH 1.0).

Second developer:

p-Methylarninophenol g 1.0 Hydroquinone g 3.0 Sodium sulphite g 13.0 Sodium carbonate g 26.0 Potassium boranocarbonate g 1.0 Potassium bromide g 1.0 Water up to 1000 ml. (pH 10.611.0).

Dye bleaching bath:

Sulphuric acid conc ml 75.0 Quinoline ml 50.0 Chinaldine m1 20.0 Sodium hypophosphite g 5.0 Potassium iodide ,g.... 40.0 Water up to 1000 ml. (pH-0).

Bleach fix bath:

Sodium ethylene diaminotetraacetate g 14.0 Sodium sulphite g 10.0 Ethylene diaminotetraacetic acid g 3.8 Iron (III) complex of ethylenediaminotetraacetic acid g 40.0

Ammonium thiosulphate g 200.0 Reaction product of ammonia and polyethylene oxide (1 mol:35 mol.) ml 1.0 Thiosemicarbazide g 1.5

Water up to 1000 ml. (pH 6.5).

Development with potassium boranocarbonate in the second developer solution yields satisfactory images without a re-exposure. When potassium boranocarbonate is omitted exposure to a 250 watt bulb for mins. at a distance of 30 cm. is necessary to obtain the same quantity of silver which is required for the complete bleaching of the azo dyes in the whites.

Potassium boranocarbonate has no effect on the dyes used. Image-wise reduction of the azo dyes in the second developer as is found, for example, with the known fogging agent, tin chloride, was not observed when using potassium boranocarbonate.

We claim:

1. In a standard photographic reversal process for use in the production of positive photographic images by image-wise exposure or" a light sensitive photographic material which contains at least one silver-halide emulsion layer, development in a black-and-white developer, fogging of the remaining silver halide and second development of the fogged material, the improvement wherein the second development is carried out in the presence of a boranocarbonate as fogging agent.

2. Process according to claim 1, wherein an alkali metal boranocarbonate is used.

3. Process according to claim 1, wherein sodium or potassium boranocarbonate is used.

4. Process according to claim 1, wherein the boranocarbonate is added to the second developer in a quantity of 0.1 to 3 g./litre. 5. Process according to claim 1, wherein a photographic material which contains a red sensitive silver halide emulsion layer with colour coupler for the production of the cyan partial image, a green sensitive silver halide emulsion layer with colour coupler for the production of the magenta partial image and a blue sensitive silver halide emulsion layer for the production of the yellow part of the image is used and that the second development is carried out with a colour forming developer.

6. Process according to claim 1, wherein a photographic material which contains a red sensitive silver halide emulsion layer with a cyano azo dye, a green sensitive silver halide emulsion layer with a magenta azo dye and a blue sensitive silver halide emulsion layer with a yellow azo dye is used, and that a negative-positive processing is carried out by the silver dye bleaching process.

References Cited UNITED STATES PATENTS 3,246,987 4/1966 Hanson et al. 96-59 3,266,895 8/1966 Perkins et al 9622 2,984,567 5/1961 Henn et al. 9659 NORMAN G. TORCHIN, Primary Examiner E. C. KIMLIN, Assistant Examiner US. Cl. X.R. 

